Abstract : A study was made of the structural state of mono- and polycrystals of Al and an alloy of Al with 3% Cu after deformation from 10 to 100% at various temperatures. Among the findings from a thorough series of tests, it was noted that with heating of an alloy for 27 hours at a temperature only 40C below the melting point, no recrystallization occurs; this gives basis for assuming that in the process of deformation of an alloy of Al with 3% Cu at 560C a polygonized state is formed which has a high stability at high temperatures. The structure of macrocrystalline samples of aluminum after deformation at 150 and 630C and an alloy of Al with 3% Cu at 560C is similar to the structure of monocrystals deformed under these same conditions. (Author)